Method and apparatus to compensate imbalance of demodulator

Abstract

Briefly, a method and apparatus to compensate for an imbalance of a demodulator by providing calibration parameters to a calibration network is provided. The apparatus may include a calibration network that may output an in-phase signal and a quadrature signal and a processor to generate calibration parameters. The processor may generate the calibration parameters by measuring an average power of the in-phase signal, an average power of the quadrature signal; and a correlation between the in-phase signal to the quadrature signal.

What is claimed is:  
     
         1 . An apparatus comprising: 
 a calibration network to output an in-phase signal and a quadrature signal; and    a processor to generate calibration parameters by measuring an average power of the in-phase signal, an average power of the quadrature signal and a correlation between the in-phase signal and the quadrature signal and to vary the calibration parameters until the in-phase signal and the quadrature signal converge to the substantially same value.    
     
     
         2 . The apparatus of  claim 1 , wherein the processor is further able to vary one or more of the calibration parameters until a product of the in-phase signal with the quadrature signal converges to substantially zero.  
     
     
         3 . The apparatus of  claim 1 , wherein the calibration network is able to compensate for impairments of the demodulator by manipulating the calibration parameters.  
     
     
         4 . The apparatus of  claim 1 , wherein the demodulator comprises a quadrature demodulator.  
     
     
         5 . The apparatus of  claim 1  further comprising: 
 a transmitter to provide a modulated test signal to the demodulator.  
 
     
     
         6 . A method comprising: 
 generating calibration parameters by measuring an average power of an in-phase signal, an average power of a quadrature signal and a correlation between the in-phase signal and the quadrature signal.    
     
     
         7 . The method of  claim 6 , further comprising: 
 varying one or more of the calibration parameters until a product of the in-phase signal and the quadrature signal converges to substantially zero.    
     
     
         8 . The method of  claim 6 , further comprising: 
 varying one or more of the calibration parameters until a power of the in-phase signal and a power of the quadrature signal converge to substantially the same value.    
     
     
         9 . The method of  claim 6 , further comprising: 
 generating the in-phase signal and the quadrature signal by demodulating a modulated test signal.    
     
     
         10 . The method of  claim 6 , wherein measuring further comprising: 
 averaging the in-phase signal;    averaging the quadrature signal; and    correlating between the in-phase signal and the quadrature signal.    
     
     
         11 . An apparatus comprising: 
 a calibration network to output an in-phase signal and a quadrature signal;    a processor to generate calibration parameters by measuring an average power of the in-phase signal, an average power of the quadrature signal and a correlation between the in-phase signal and the quadrature signal and to vary one or more of the calibration parameters until the in-phase signal and the quadrature signal converge to the substantially same value; and    a direct sequence spread spectrum transmitter to provide a test signal to the calibration network.    
     
     
         12 . The apparatus of  claim 11 , wherein the processor is further able to vary the calibration parameters until a product of the in-phase signal with the quadrature signal converges to substantially zero.  
     
     
         13 . The apparatus of  claim 11 , wherein the calibration network is able to compensate for impairments of the demodulator by manipulating the calibration parameters.  
     
     
         14 . The apparatus of  claim 11 , wherein the demodulator comprises a quadrature demodulator.  
     
     
         15 . The apparatus of  claim 11 , wherein said transmitter is able to provide said test signal to the demodulator.  
     
     
         16 . An article comprising a storage medium having stored thereon instructions that when executed result in: 
 generating calibration parameters by measuring an average power of an in-phase signal, an average power of quadrature signal; and a correlation between the in-phase signal to the quadrature signal.    
     
     
         17 . The article of  claim 16 , wherein the instructions when executed further result in: 
 varying one or more of the calibration parameters until a product of the compensated in-phase signal and the compensated quadrature signal converges to substantially zero.    
     
     
         18 . The article of  claim 16 , wherein the instructions when executed further result in: 
 varying one or more of the calibration parameters until a power of the in-phase signal and a power of the quadrature signal converge to substantially the same value.    
     
     
         19 . The article of  claim 16 , wherein the instructions when executed further result in: 
 generating the in-phase signal and the quadrature signal by demodulating a modulated test signal.    
     
     
         20 . The article of  claim 16 , wherein the instructions of measuring when executed further result in: 
 averaging the in-phase signal;    averaging the quadrature signal; and    correlating between the in-phase signal and the quadrature signal.